The above discussion of socioeconomic "thresholds" for fertility reduction is obviously exploratory and not conclusive. Their predictive value for determining the prospective onset of natality transition is yet to be fully tested. The evidence so far does suggest that there are regularities in the relationships between socioeconomic development and natality within major cultural regions that may prove useful, jointly with other approaches, in forecasting the "take-off point for sustained fertility declines.*
The examination of recent trends in natality in the less developed regions tends to confirm the first three propositions presented at the outset. The data support the following conclusions about recent changes in natality in less developed regions:
1. A growing number of countries have been entering the demographic transition on the natality side since World War II and after a lapse of some 25 years in which no major country entered this transition.
2. Once a sustained reduction of the birth rate has begun, it proceeds at a much more rapid pace than it did historically in Europe and among Europeans overseas.
3. The "new" countries may reduce birth rates quite rapidly despite initially higher levels than existed historically in western Europe.
4. Where available, the more refined measures of fertility, standardizing for differences in age structure, yield results similar to those for crude birth rates.
5. There is no direct evidence yet that current fertility reductions will terminate at levels significantly higher than those achieved in European countries and Japan.
As earlier noted, the above observations are based primarily on the experience of a relatively few countries with good data. Similar reductions in natality are very likely occurring in a number of other countries lacking reliable annual vital statistics. But there is no evidence yet as to whether reductions in the birth rate have recently occurred, or not occurred, in large countries, such as China, India, Pakistan, and Indonesia. What is happening in these countries will be crucial.
Efforts to identify "thresholds" for the initiation of fertility reduction are at a preliminary stage and their predictive capacity, although promising in
*The above analysis has quite consciously used incomplete and sometimes dubious data to evaluate changes that may have appeared in very recent years. It is, of course, not intended to replace much more detailed analysis of better data that will become available in due course. Obviously it complements rather than eliminates the need for study of specific causal relationslu'ps between socioeconomic development, changes in motivations regarding desired family size, and the degree of success in the actual practice of family limitation.,.,..„ Tn;..,n~ u~.,,, !/•„„„ \/i*in,,r, o:-----«,.,„ .....i r>~,,i.*..atly varying quality, single figures should not be taken very seriously. Thus the extraordinarily high correlation of telephones (i.e., a surrogate for modern infrastructure) with natality is reduced from -0.94 to -0.88 when Argentina and Uruguay arc excluded.